SELF-ALIGNED POLYSILICON FET DEVICE SEPARATED BY SHALLOW TRENCH SEPARATION AND GATE CONDUCTOR FILLING TECHNOLOGIES AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To make shallow trench separation by a method wherein a conformal silicon oxide layer on a mesa is partially etched by selective RIE and then the silicon oxide layer is transformed to a flat silicon oxide layer using a silicon nitride pad as an etch stopper and then a conformal blanket silicon oxide layer is polished chemically and mechanically. SOLUTION: An RIE etchant is introduced from openings 48A, 48B, 48C into etching openings 50A, 50B, 50C formed inside through a gate insulating layer 44 extended through a tungsten silicide layer 42 and a doped polysilicon layer 40. Then, the surfaces of gate oxide layer segments 38/38' are exposed with a gate conductor stack 51 having source/drain windows on both sides of an N well 34 and having a dummy window wherein a P well is exposed for the later ion implantation being left over. After that, the entire surface is covered by the silicon nitride gate insulating layer 44 and then the insulating layer 44 is polished chemically and mechanically.